This revised R21 (in response to PA-06-343 Methodology And Measurement In The Behavioral And Social Sciences) proposes one of the first rigorous applications of ESM (Experience Sampling Methods) to quantify sexual behavior, contraceptive use, and mood in a developing country. In collaboration with experienced researchers in Cebu, Philippines, we will develop and modify procedures with a pilot study of 32 individuals and then conduct a randomized trial with 800 Filipino young adults with the following randomized elements: " Weekly troubleshooting phone calls versus no phone calls " Participant-driven versus randomly timed prompts to complete a questionnaire on a Personal Digital Assistant (PDA) " Face-to-Face versus paper and pencil self-administered questionnaires for exit interviews Our Specific Aims are as follows: Aim 1: Compare rates of acceptance, completion and data quality across populations and randomized elements Aim 2: Compare reporting of sexual activity, contraceptive use and mood between ESM and other methods. Aim 3: Examine the interrelationships between mood, sexual activity and contraception. Nearly all surveys on sexual health of Filipinos have been done with face-to-face interviews. Computerized surveys to report sensitive behaviors may be an alternative for young adults. We will weigh the costs of technology, interviewer and field team time, as well as participant burden against the potential gains of using technology compared to face-to-face and self administered questionnaires. The wealth of data collected in this project will serve as a basis for research questions, hypothesis testing and hypothesis generation well beyond the aims of this proposal. PUBLIC HEALTH RELEVANCE We will develop methods for collecting daily data on sensitive behaviors and feelings using the most rigorous randomized study design. This study will lead to a detailed characterization of young adults'health and mood among 800 young adults in the Philippines. Personal Data Assistants (PDAs) will be used to measure important aspects of health in the developing world.